/Engine/Source/Runtime/GeometryCore/Public/Selections/MeshConnectedComponents.h
Find all connected vertex components of a subset of vertices of the Mesh and store in Components array.
void FindConnectedVertices ( const [TArray](API\Runtime\Core\Containers\TArray)< int > & VertexROI, [TFunction](API\Runtime\Core\GenericPlatform\TFunction)< bool(int32, int32)> VertsConnectedPredicate )